A school water system has been infected with the legionella bacteria.
Signs of the bacteria were discovered during an annual check at Chatham and Clarendon Grammar School in Ramsgate.
After the results came back, the school's water quality consultant cleaned and disinfected the system and were on site for four days.
If legionella bacteria is inhaled by people it can cause a serious lung infection called legionnaires’ disease.
Initial symptoms can include headaches, muscle pain, high temperature or chills.
The bacteria can then infect the lungs, which causes people to experience symptoms of pneumonia, potentially leading to chest pain, shortness of breath and coughing up blood.
Severe infections can cause some organs, such as the lungs or kidneys, to stop working properly.
Signs of the bacteria were first discovered at the school in June and experts visited the site after test results came back positive in mid-July, but details have only just emerged.
Testing was done on 36 different sites across the school and four had readings for the bacteria.
"There were no health scares or issues and no reported cases of legionnaires' disease" - Chris Freeman, school business manager
School business manager Chris Freeman said: "The readings were only found in staff areas of the school such as the male shower and toilet.
"We were told it was in ‘dead legs’ of the water, which are supplies that aren’t used.
"We didn’t let the children know because they weren’t exposed to it.
"We let staff know because they would have been.
"The company that came in cleansed all of the school systems, even ones without readings, just to be safe.
"We were assured it wasn’t serious and there will be a retest in three months.
"There were no health scares or issues and no reported cases of legionnaires' disease."
Legionnaires' disease is normally caught by breathing in small droplets of contaminated water. The infection cannot be spread from person to person.
Large buildings are more vulnerable to legionella contamination because of their complex water supply systems, allowing the bacteria to spread more quickly.
Artificial water supply systems also allow the bacteria to multiply rapidly.
Rust or limescale are both common things on which the bacteria can feed.
The NHS website says everyone is potentially at risk but the disease is rare in the UK with only 284 people reported to have had the condition in 2013.
Public Health England spokesman Sarah Kennedy said: "We aware of the incident and can confirm that to date there have been no legionnaires cases associated with this incident.
"We understand that appropriate control measures are being implemented by the school authorities.
"Legionella bacteria are widely distributed in the environment and are commonly found in artificial water sources such as cooling systems, domestic water systems and spa pools.
"People become infected when they inhale legionella bacteria as airborne particles arising from a contaminated source.
"Employers and service providers are required to identify and mitigate the risks of legionella from environmental exposure."